Response times have been used to explore cognitive and perceptual processes since 1850 (Donders, 1868). The technique has primarily been applied to humans, birds, and terrestrial mammals. Results from two studies are presented here that examine response times in bottlenose dolphins (Tursiops truncatus) and white whales (Delphinapterus leucas). One study concerned response times to stimuli well above the threshold of perceptibility of a stimulus, and the other concerned response times to stimuli near threshold. Two white whales (Delphinapterus leucas) and five Atlantic bottlenose dolphins (Tursiops truncatus) were presented stimuli well above threshold. The stimuli varied in type (tone versus pulse), amplitude, duration, and frequency. The average response time for bottlenose dolphins was 231.9 ms. The average response time for white whales was 584.1 ms. There was considerable variation between subjects within a species, but the difference between species was also found to be significant. In general, response times decreased with increasing stimulus amplitude. The effect of duration and frequency on response time was unclear. Two white whales (Delphinapterus leucas) and four Atlantic bottlenose dolphins (Tursiops truncatus) were given audiometric tests to determine masked hearing thresholds in open waters of San Diego Bay (Ridgway et al., 1997). Animals were tested at six frequencies over a range from 400 Hz to 30 kHz using pure tones. Hearing thresholds varied from 87.5 dB to 125.5 dB depending on the frequency, masking noise intensity and individual animal. At threshold, median response time across frequencies within each animal varied by about 150 ms. The two white whales responded significantly slower (∼670 msec, p<0.0001) than the four dolphins (∼410 msec). As in terrestrial animals, reaction time became shorter as stimulus amplitude increased (Wells, 1913; Stebbins, 1966). Across the two studies, the dolphins as a group were faster in the abovethreshold study than in the nearthreshold study. White whales had longer response times than bottlenose dolphins in both studies. Analysis of response time with an allometric relation based on weight shows that the difference in weight can explain a significant part of the difference in response time.

The heterogeneous landscape of Florida Bay provides habitats for a variety of predators and prey. This dissertation examined the bottom-up transfer of affects from environmental variability through prey composition up to competition and predation affects on top predator distribution and foraging ecology in Florida Bay. Line transect surveys for bottlenose dolphins and seabirds were conducted in Florida Bay during the summer months of 2002 - 2005. Photo-identification techniques were implemented to identify individual dolphins. Synoptic with this survey effort, habitat characteristics (temperature, salinity, dissolved oxygen, turbidity, chlorophyll a, depth and bottom type) and prey composition (bottom trawl or gillnet) were sampled. Comparison of envelope maps from generalized additive models determined that predictive capacity of dolphin habitat did not improve by incorporating fish distribution data. However, models of dolphin distribution based solely on environmental proxies of fish distribution resulted in high predictive capacity. During the 2005 summer, shark distribution was sampled using a longline. The abundance of sharks was only correlated to fish catch from trawls on a regional scale. Larger sharks, of species that may threaten dolphins, were only caught in the Gulf zone of the Bay. Analysis of dolphin distribution revealed high individual site and foraging tactic fidelity. Dolphins were spatially coincident with habitat characteristics that encouraged the use of each individual's preferred foraging tactic. Depth was identified as the primary variable determining dolphin foraging tactic choice. Depth plays a significant role in the benthic composition of Florida Bay, which subsequently impacts prey communities and affects dolphin distribution, foraging and social ecology. Ordinations determined that fish distribution was also principally affected by depth and bottom type. Shallow environments frequently corresponded with mudbank habitat (depth < 1m) where the sighting rates of seabirds (cormorants, osprey, pelicans, terns) and foraging dolphins peaked. In conclusion, subtle relief in South Florida's bedrock topography dramatically affect benthic composition within Florida Bay, providing patchy habitats for prey and predators. The Florida Bay ecosystem will change with expected sea level rise, including spatial shifts of mudbank habitats. Top predator populations in Florida Bay will be forced to modify their distribution and foraging ecology accordingly. / Dissertation

In the Eastern Tropical Pacific (ETP), the operation mode of purse-seine fishing can be divided into dolphin sets and non-dolphin sets. Dolphin sets can catch more yellowfin tuna, but cause a lot of dolphin deaths. On the contrary, non-dolphin sets can catch more skipjack tuna, but discard a lot of tuna. Therefore, the choice of the operation mode to the ETP purse-seine fishery is very influential. If the fishermen use more dolphin sets, they are able to catch high quantity and more valuable yellowfin tuna. Conversely, if the fishermen use more non-dolphin sets, they will not hurt dolphins. But the tuna fish caught by this operation mode is smaller in size and the discarding rate is extremely high which will affect the overall profits of the fishermen. The research will investigate how the fishermen make the choice of the operation mode in the dilemma between dolphin sets which cause dolphins-bycatch and non-dolphin sets which result in tuna-discarding, In addition, if managers can ban dolphin sets or non-dolphin sets to maximize the profit of the fishermen and maintain the ecological balance between tuna and dolphins.

Die vorliegende Arbeit befasst sich mit der wissensbasierten Modellierung von Audio-Signal-Klassifikatoren (ASK) für die Bioakustik. Sie behandelt ein interdisziplinäres Problem, das viele Facetten umfasst. Zu diesen gehören artspezifische bioakustische Fragen, mathematisch-algorithmische Details und Probleme der Repräsentation von Expertenwissen. Es wird eine universelle praktisch anwendbare Methode zur wissensbasierten Modellierung bioakustischer ASK dargestellt und evaluiert. Das Problem der Modellierung von ASK wird dabei durchgängig aus KDD-Perspektive (Knowledge Discovery in Databases) betrachtet. Der grundlegende Ansatz besteht darin, mit Hilfe von modifizierten KDD-Methoden und Data-Mining-Verfahren die Modellierung von ASK wesentlich zu erleichtern. Das etablierte KDD-Paradigma wird mit Hilfe eines detaillierten formalen Modells auf den Bereich der Modellierung von ASK übertragen. Neunzehn elementare KDD-Verfahren bilden die Grundlage eines umfassenden Systems zur wissensbasierten Modellierung von ASK. Methode und Algorithmen werden evaluiert, indem eine sehr umfangreiche Sammlung akustischer Signale des Großen Tümmlers mit ihrer Hilfe untersucht wird. Die Sammlung wurde speziell für diese Arbeit in Eilat (Israel) angefertigt. Insgesamt werden auf Grundlage dieses Audiomaterials vier empirische Einzelstudien durchgeführt: - Auf der Basis von oszillographischen und spektrographischen Darstellungen wird ein phänomenologisches Klassifikationssystem für die vielfältigen Laute des Großen Tümmlers dargestellt. - Mit Hilfe eines Korpus halbsynthetischer Audiodaten werden verschiedene grundlegende Verfahren zur Modellierung und Anwendung von ASK in Hinblick auf ihre Genauigkeit und Robustheit untersucht. - Mit einem speziell entwickelten Clustering-Verfahren werden mehrere Tausend natürliche Pfifflaute des Großen Tümmlers untersucht. Die Ergebnisse werden visualisiert und diskutiert. - Durch maschinelles mustererkennungsbasiertes akustisches Monitoring wird die Emissionsdynamik verschiedener Lauttypen im Verlaufe von vier Wochen untersucht. Etwa 2.5 Millionen Klicklaute werden im Anschluss auf ihre spektralen Charakteristika hin untersucht. Die beschriebene Methode und die dargestellten Algorithmen sind in vielfältiger Hinsicht erweiterbar, ohne dass an ihrer grundlegenden Architektur etwas geändert werden muss. Sie lassen sich leicht in dem gesamten Gebiet der Bioakustik einsetzen. Hiermit besitzen sie auch für angrenzende Disziplinen ein hohes Potential, denn exaktes Wissen über die akustischen Kommunikations- und Sonarsysteme der Tiere wird in der theoretischen Biologie, in den Kognitionswissenschaften, aber auch im praktischen Naturschutz, in Zukunft eine wichtige Rolle spielen. / The present thesis is dedicated to the problem of knowledge-based modeling of audio-signal-classifiers in the bioacoustics domain. It deals with an interdisciplinary problem that has many facets. To these belong questions of knowledge representation, bioacoustics and algorithmical issues. The main purpose of the work is to provide and evaluate a scientific method in which all these facets are taken into consideration. In addition, a number of algorithms, which implement all important steps of this method, are described. The problem of modeling audio-signal-classifiers is regarded from the KDD-perspective (Knowledge-Discovery in Databases). The fundamental idea is to use modified KDD- and Data-Mining-algorithms to facilitate the modeling of audio-signal-classifiers. A detailed mathematical formalism is presented and the KDD-paradigm is adopted to the problem of modeling audio-signal-classifiers. 19 new KDD-procedures form a comprehensive system for knowledge-based audio-signal-classifier design. An extensive collection of acoustic signals of the bottlenose-dolphin was recorded in Eilat (Israel). It forms the basis of four empirical studies: A phenomenological classification of acoustic phenomena, an experimental evaluation of accuracy and precision of classifiers, a cluster analysis of whistle sounds and a monitoring study to examine the nature of click sounds. Both, method and algorithms can be adopted to other branches in bioacoustics without changing their fundamental architecture.

Response times have been used to explore cognitive and perceptual processes since 1850 (Donders, 1868). The technique has primarily been applied to humans, birds, and terrestrial mammals. Results from two studies are presented here that examine response times in bottlenose dolphins (Tursiops truncatus) and white whales (Delphinapterus leucas). One study concerned response times to stimuli well above the threshold of perceptibility of a stimulus, and the other concerned response times to stimuli near threshold. Two white whales (Delphinapterus leucas) and five Atlantic bottlenose dolphins (Tursiops truncatus) were presented stimuli well above threshold. The stimuli varied in type (tone versus pulse), amplitude, duration, and frequency. The average response time for bottlenose dolphins was 231.9 ms. The average response time for white whales was 584.1 ms. There was considerable variation between subjects within a species, but the difference between species was also found to be significant. In general, response times decreased with increasing stimulus amplitude. The effect of duration and frequency on response time was unclear. Two white whales (Delphinapterus leucas) and four Atlantic bottlenose dolphins (Tursiops truncatus) were given audiometric tests to determine masked hearing thresholds in open waters of San Diego Bay (Ridgway et al., 1997). Animals were tested at six frequencies over a range from 400 Hz to 30 kHz using pure tones. Hearing thresholds varied from 87.5 dB to 125.5 dB depending on the frequency, masking noise intensity and individual animal. At threshold, median response time across frequencies within each animal varied by about 150 ms. The two white whales responded significantly slower (∼670 msec, p<0.0001) than the four dolphins (∼410 msec). As in terrestrial animals, reaction time became shorter as stimulus amplitude increased (Wells, 1913; Stebbins, 1966). Across the two studies, the dolphins as a group were faster in the abovethreshold study than in the nearthreshold study. White whales had longer response times than bottlenose dolphins in both studies. Analysis of response time with an allometric relation based on weight shows that the difference in weight can explain a significant part of the difference in response time.

Skin and blubber tissue samples were collected from two hundred and six freeranging Heaviside’s dolphins (Cephalorhyncus heavisidii) during January through June of 2008, 2009, and 2010, along the coast of South Western Africa, to be analyzed for heavy metal concentration levels. Inductively coupled mass spectrometry (ICP-MS) was used to determine sample solution concentrations of all metals (aluminum, arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium and zinc). Data provided by this thesis is the first reference of its kind for this species (Cephalorhyncus heavisidii), which is one of the least-known cetacean species in the world. In addition to baseline heavy metal concentration information for the Heaviside’s dolphin, meaningful population structural and ecological information was obtained. A level of site fidelity or specific movement pattern across certain sites was indicated by the presence of different concentration levels across individuals sampled in different areas, especially adjacent areas. With an investigation into the potential sources of the marine heavy metal contamination, it was deduced that these sources contributed to each site’s unique and characteristic toxicological and hydrological profile as reflected by the bioaccumulation patterns seen in this study. It was confirmed by this study that bioaccumulation levels are a meaningful and novel measure of population structure. Potential evidence of differences in bioaccumulation patterns between sexes was observed in this study, as well. Although not definitive, a difference in metabolism, heavy metal elimination, or ranging pattern between males and females was suggested by the results. Variation in the results suggests a deepened level of complexity in the physiological and ecological aspects of trace elements accumulation and detoxification in the tissue of an apex predator like the Heaviside’s dolphin. Finally, a general assessment of health implications for the species was established, and it was found that Heaviside’s dolphins have higher than average mammalian trace element concentrations, and higher than average concentrations as specifically compared with other odontocetes. Further research using a larger sample size and using internal organs will provide more insight and a deeper understanding of the novel information presented here. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

Freshwater ecosystem degradation in the Amazon and Orinoco river basins is increasing due to rising human population numbers, and large water development projects. Therefore, monitoring ecosystem condition in these rivers of high biodiversity is of global conservation importance. This dissertation evaluated the potential of using river dolphins as indicators of ecosystem condition in large tropical rivers of South America. First, population estimates of river dolphins were obtained by line-strip transect surveys and mark-recapture methods on photo-identifications. Using this information, I identified critical habitat, hotspots, and areas of concern for river dolphins, as well as the relationship between dolphin density and group size estimates with ecological features. Second, I evaluated the relationship between dolphin estimates and human stressors. Higher densities of dolphins occurred in rivers with low indices of overall freshwater degradation, such as rivers with high water quality and the lowest human population numbers. Thus, dolphin density estimates seem to be good indicators of freshwater ecosystem degradation in the Amazon and Orinoco basins. These top predators not only are indicator species, but also have the potential to act as flagship and sentinel species, indicating freshwater ecosystem degradation and stimulating conservation action. This dissertation highlights the large changes in the Amazon and Orinoco that are approaching fast. Indicator, flagship and sentinel species can become science-based conservation tools not to only document freshwater ecosystem degradation, but to raise awareness about broader implications of human stressors on biodiversity and river systems.

Greater knowledge of the rough-toothed dolphin, Steno bredanensis, is needed to effectively contribute to conservation and management efforts for this species. The primary purpose of this research was to describe ecological and biological parameters for S. bredanensis that will be useful in future assessments of population stress. Several approaches were used to study S. bredanensis, including investigations of free-ranging populations, dead specimens, and captive individuals. Free-ranging rough-toothed dolphins distributed near small oceanic island environments were found to be more commonly sighted in-shore than off-shore. In the Windward islands of French Polynesia, this species preferred water depths of 1000 to 2000m and a distance of 1.8 to 5.5 km from the barrier reef. Group sizes ofrough-toothed dolphins sighted in French Polynesia range between 1 and 35 individuals with a mean size of 12.1. Endocrinology data for S. bredanensis was established in captive healthy and stranded individuals. Ranges and means were provided for progesterone, testosterone, cortisol and thyroid hormones. Changes in thyroid hormone concentrations were reflective of health status and testosterone appeared to be suppressed in ill individuals. Reproduction in S. bredanensis was investigated by determining the size and age range that this species attains sexual and physical maturity. Female rough-toothed dolphins attain sexual maturity by 9 to 10 years of age and males between 5 and 10 years at a similar length of approximately 216 cm. Physical maturity is generally reached at an older age and larger size for both males and females. Ecologically healthy and unheahhy populations of S. bredanensis were described in this investigation and these fmding will be useful in assessing future threats to this species.

Greater knowledge of the rough-toothed dolphin, Steno bredanensis, is needed to effectively contribute to conservation and management efforts for this species. The primary purpose of this research was to describe ecological and biological parameters for S. bredanensis that will be useful in future assessments of population stress. Several approaches were used to study S. bredanensis, including investigations of free-ranging populations, dead specimens, and captive individuals. Free-ranging rough-toothed dolphins distributed near small oceanic island environments were found to be more commonly sighted in-shore than off-shore. In the Windward islands of French Polynesia, this species preferred water depths of 1000 to 2000m and a distance of 1.8 to 5.5 km from the barrier reef. Group sizes ofrough-toothed dolphins sighted in French Polynesia range between 1 and 35 individuals with a mean size of 12.1. Endocrinology data for S. bredanensis was established in captive healthy and stranded individuals. Ranges and means were provided for progesterone, testosterone, cortisol and thyroid hormones. Changes in thyroid hormone concentrations were reflective of health status and testosterone appeared to be suppressed in ill individuals. Reproduction in S. bredanensis was investigated by determining the size and age range that this species attains sexual and physical maturity. Female rough-toothed dolphins attain sexual maturity by 9 to 10 years of age and males between 5 and 10 years at a similar length of approximately 216 cm. Physical maturity is generally reached at an older age and larger size for both males and females. Ecologically healthy and unheahhy populations of S. bredanensis were described in this investigation and these fmding will be useful in assessing future threats to this species.

Hector�s dolphin (Cephalorhynchus hectori) is an endangered coastal species endemic to New Zealand. Their distribution, like other marine organisms, is intertwined with the dynamics of their local habitats, and at a larger scale, the coastal waters around New Zealand. The main purpose of this thesis was to identify specific habitat requirements of this rare dolphin. Hector�s dolphin distribution around the South Island was quantified along several temporal and spatial scales. Large-scale density analyses of abundance surveys found over half of the South Island�s current population occurred within only three main regions. Two of these strongholds are along the west coast and the third is located around Banks Peninsula on the east coast. Smaller-scale analyses at Banks Peninsula found the majority of the dolphin community was preferentially using core regions within the marine mammal sanctuary. Monthly surveys showed that in summer and autumn statistically more dolphins occurred within inshore regions ([less than or equal to]one kilometre), spread throughout the surveyed coastline. From May through winter, dolphin densities rapidly declined. Remaining dolphins were significantly clumped in more offshore waters of eastern regions. The lowest encounter rates occurred between August and September. Certain 'hotspots' consistently had higher dolphin densities throughout the study period while others were preferred seasonally. To address habitat preferences, surveys simultaneously collected oceanographic samples using a CTD profiler. In general, physical variables of the Peninsula�s eastern and southeastern waters varied less, despite being regularly exposed to upwellings and the varied presence of sub-tropical waters. Semi-sheltered bays and shallow inshore waters were highly variable and more susceptible to spatially discrete influences, such as localised river outflows and exchange events. Several hydrographic features were seasonally predictable due to their dependence on climate. The stratification and location of the two dominant water masses (neritic and sub-tropical) accounted for over half of the temporal and spatial variability observed in oceanographic data. Possible relationships between oceanographic features and aggregations of dolphins within Banks Peninsula were examined using global regression and a spatial technique known as geographical weighted regression (GWR). GWR models out-performed corresponding global models, despite differences in degrees of freedom and increased model complexity. GWR results found relationships varied over localised scales that were concealed by global methods. Monthly GWR models suggested the seasonal presence and strength of local oceanographic fronts influenced dolphin distribution. Dolphin aggregations coincided with the steepest gradients between water masses along eastern regions of the Peninsula, and strong exchange events along the edges of the study area. The continued survival of this endangered species is contingent on its protection. Long-term monitoring programmes are needed for the three main strongholds identified in this study. The occurrence of Hector�s dolphin 'hotspots' along frontal zones within Banks Peninsula also suggests alternative and increased protection strategies are needed for this sanctuary to be effective. In light of this thesis� findings and based on marine protection research, future sanctuaries need to consider why Hector�s dolphins are preferentially using particular regions and how their association with certain oceanographic features can help make informed decisions on more appropriate protected areas.